It has been known that a low density lipoprotein (LDL) receptor in hepatic cells plays an important role in the regulation of cholesterol level in the blood. That is, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor inhibits the synthesis of cholesterol in hepatic cells, by which the expression of LDL receptor is indirectly promoted. As a result, the uptake of LDL by a LDL receptor from the blood is increased, and then the cholesterol level in the blood is reduced.
In addition, 1,2,4-triazine derivatives are disclosed, for example, in Liebigs Annalen der Chemie, p. 631, 1990; Chemical and Pharmaceutical Bulletin, p. 926, 1973; Yakugaku-Zasshi, vol. 112, p. 729, 1992; Journal of Organic Chemistry, vol. 52, p. 4287, 1987; Japanese Patent Publication No. 63-225366; Japanese Patent Publication No. 5-45816, etc., but these derivatives have not been known as an LDL receptor gene expression promoter or as an agent for treatment of hyperlipidemia.